Polymeric articles having embedded phases

ABSTRACT

A die apparatus, a method of using the die apparatus to produce co-extruded polymeric articles, and co-extruded polymeric articles produced using the die apparatus and method are disclosed. The die apparatus includes a hollow vane configured to extrude a material into a chamber within the die, thereby producing a co-extruded web. The co-extruded web has a plurality of distinct, discontinuous phases in the cross-web direction, the phases having a uniform width as shown by a coefficient of variation of less than 8 percent for, any three consecutive phases. The phases are substantially continuous down-web and are surrounded by a matrix having two or more layers.

FIELD OF THE INVENTION

The present invention is directed to an extrusion die, a method of usingthe die to produce co extruded polymeric articles, and co-extrudedpolymeric articles produced therewith having internal discontinuities,such as stripes.

BACKGROUND OF THE INVENTION

Extruded polymeric webs are used in many applications, including theproduction of thin films for use as tape backings, medical films, andvapor barriers. Polymeric materials that are suitable for extrusion areoften polyolefins such as polyethylene, polypropylene, and polybutylene,polyamides such as nylon; polyesters such as polyethylene terephthalateor polyvinylidene fluoride. Although these polymeric materials andothers are suitable for use in forming a polymeric web, they can havelimiting characteristics that substantially narrow their suitable uses.For example, reinforced polypropylene webs often have very good tensilestrength, but have less than desirable cross-web tear strength.Therefore, due to a propensity to tear too easily in the cross-webdirection, oriented polypropylene webs do not traditionally makesatisfactory products requiring cross-web strength, such as strappingtape products. Similarly, natural and synthetic rubber have excellentelasticity, but are difficult to fuse with most polymeric materials.Therefore, due to the challenge of creating a good bond betweenmaterials, rubber webs are difficult to use in products that requirethem to be joined with other polymeric materials.

A hybrid polymeric web combining two polymers is described in Krueger etal. (U.S. Pat. No. 5,429,856). An apparatus for making a co-extruded webis disclosed in Schrenk et al. (U.S. Pat. No. 3,485,912).

DISCLOSURE OF INVENTION

In certain embodiments of the invention, the polymeric co-extruded webcomprises a plurality, of uniform, distinct, phases (embedded phases)that are discontinuous in a cross-web direction. The embedded phasespreferably have a width uniform to within a coefficient of variation ofless than 8 percent for three consecutive discontinuous phases. Thewidth of these embedded phases is measured in a cross-section of theco-extruded web cut transverse (i.e., cross-web) to the machinedirection (i.e., down-web) and is the largest dimension of thecross-section of the embedded phases in the cross-web direction. Theembedded phases are substantially continuous down-web and are surroundedby a matrix having two or more distinct layers of the same or differentmaterials.

In one embodiment, the discontinuous phases of the polymeric co-extrudedweb are spaced at substantially uniform intervals in the cross-webdirection. In another embodiment, the plurality of discontinuous phasesconsists of a first discontinuous phase positioned proximate a firstedge of the web, and a second discontinuous phase positioned proximate asecond edge of the web.

The present invention is also directed to an extrusion die for forming apolymeric co-extruded web. In specific embodiments, the die includes abody containing two chambers. An adjustable vane is positioned betweenthe chambers. The adjustable vane is at least partially hollow, having acavity within its interior. The vane has at least one opening (inlet) inthe cavity positioned to receive a material being extruded, and at leasttwo openings (outlets) in the cavity positioned in a tip to extrudematerial into the body of the die. The cavity inlets and outlets aresized so that the width of the embedded phases extruded from the vaneoutlets into the die body are uniform. This uniformity of the embeddedphases is an advantage of this invention.

In operation, a first material is forced into the chambers of the bodyof the die, and a second material is forced into the cavity of the vane.The first material is conveyed through the chambers of the die, passingaround and past the vane. The second material enters the cavity of thevane and subsequently flows out through the tip of the vane orientedtoward the downstream end of the die and into the die body, where itflows along with the first material in laminar flow until the combinedmaterials exit the die to form a co-extruded web.

The invention is further directed to a process of making a polymericco-extruded web. The process includes providing an extrudable materialand an extrusion die. In a specific embodiment, the die contains twochambers and an adjustable vane between the chambers. The vane containsa cavity having at least one input orifice positioned to receiveextrudable material and at least two exit orifices. The cavity isdesigned so that the pressure drop of molten polymer within the cavityis significantly less than the pressure drop through the exit orificesto yield embedded phases of improved width uniformity over thoseextruded by known techniques. A first material is extruded through thechambers of the die, and a second material is extruded through the exitorifice in the vane to produce a co-extruded web containing the firstand second extrudable materials. The second material is embedded betweenthe two layers of the first material. Alternatively, different polymericmaterials may pass through each die chamber to form two layers ofdifferent materials that are positioned around the embedded phasematerial.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a system for production of a co-extrudedweb in accordance with an embodiment of the invention.

FIG. 2A is a perspective view of an extrusion die constructed inaccordance with an embodiment of the invention.

FIG. 2B is a perspective view of an extrusion die vane constructed inaccordance with an embodiment of the invention.

FIG. 2C is a partial perspective view of a tip of a die vane constructedin accordance with an embodiment of the invention.

FIG. 3A is a cross-sectional view of the extrusion die shown in FIG. 2A,taken along plane 3A of FIG. 2A.

FIG. 3B is a cross-sectional view of the extrusion die shown in FIG. 2A,taken along section line 3B of FIG. 3A.

FIG. 4 is a perspective view of a polymeric web made in accordance withthe invention and showing the web in cross-section.

FIG. 5A is an end view of an extrusion die vane constructed inaccordance with an embodiment of the invention

FIG. 5B is an end view of an extrusion die vane constructed inaccordance with the embodiment depicted in FIG. 2C.

FIG. 5C is an end view of an extrusion die vane constructed inaccordance with another embodiment of the invention.

FIG. 5D is an end view of an extrusion die vane constructed inaccordance with another embodiment of the invention.

FIG. 6A is a cross-sectional view of a polymeric web made in accordancewith an embodiment of the invention.

FIG. 6B is a cross-sectional view of a polymeric web made in accordancewith another embodiment of the invention.

FIG. 6C is a cross-sectional view of a polymeric web made in accordancewith yet another embodiment of the invention.

FIG. 7A is a cross-sectional view of a polymeric web constructed inaccordance with an embodiment of the invention.

FIG. 7B is a perspective view of a box closed with a sealing web or tapemade in accordance with an embodiment of the invention.

FIG. 8 is a photo-micrograph of a cross section of a polymeric web madein accordance with an embodiment of the invention shown in Example 10.

FIG. 9 is a photo-micrograph of a cross section of a polymeric web madein accordance with an embodiment of the invention shown in Example 13.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a schematic view of an extrusion system 10 formanufacturing a co-extruded polymeric web 12 in accordance with anembodiment of the invention. In the embodiment depicted, system 10includes extruders 14 and 16, as well as an extrusion die 18. Theextruders 14 and 16 respectively contain first and second extrudablematerials 15 and 17 and provide molten streams of first and secondextrudable materials 15 and 17 along conduits 20 and 22 to extrusion die18. As detailed below, the extrudable materials 15 and 17 are extrudedfrom the die 18 Such that first extrudable material 15 substantiallysurrounds or forms a matrix around second extrudable material 17, whichbecomes the discontinuous phases embedded within the matrix having twolayers. Alternatively, a third extruder may be used to feed a thirdmaterial into the die 18 to form a matrix having a different materialfor each matrix layer.

The manner in which the co-extruded web 12 is formed is shown in moreparticularity in FIGS. 2A through 3B. In addition, FIG. 4 shows anembodiment of the co-extruded web 12 produced by use of system 10. Withreference now to FIG. 2A, a perspective view of the extrusion die 18 isdepicted showing a body 24 that has at least first and second orifices26 and 28. Orifice 26 provides entry for the first extrudable material15 from conduit 20, while orifice 28 provides entry for the secondextrudable material 17 from conduit 22. Optionally, the first materialcould be passed thorough orifice 26A and the third material could bepassed through orifice 26B. In addition, a second embedded phasematerial could be introduced through orifices 28 on the sides of die 18.However, in that case, a separating means (e.g., partition) within vane44 preferably would be added to prevent mixing of the two embedded phasematerials within vane 44. Extrusion die 18 also includes an exit port30. The width of port 30 (also called the die gap) is typically 1000 μmor less, for elastic webs typically 100-250 μm.

The extrudable materials 15 and 17 enter extrusion die 18 at orifices 26and 28, respectively, flow through die 18, and then leave die 18 at exitport 30 as co-extruded web 12. Therefore, die 18 has a generallyupstream end 32 and a generally down stream end 34. In addition, in theembodiment represented, die 18 includes a top 36, an opposite bottom 38,a first side 40 and an opposite second side 42.

Within extrusion die 18 is an adjustable vane 44, shown in FIG. 2B.Adjustable vane 44 includes at least two types of orifices 46 and 50.Entrance orifice or orifices 46 allow entry of polymeric material 17into the interior of vane 44, and outlet orifice 50 permit the exit ofpolymeric material 17 from the interior of vane 44. In the embodimentdepicted, entrance orifices 46 (one not shown) are positioned along aside of back section 48 of vane 44. Also in the embodiment depicted, aplurality of outlet orifices 50 are positioned along front 51 of vane 44at downstream end 52 of vane 44. The outlet orifices can be made by EDM(electro-discharge machining) or other material removal means known inthe art. The shape and position of orifices 50 define the shape andposition of the plurality of distinct embedded phases in the polymericweb. Advantageously, tip 53 of vane 44 may be removable and replaceableto allow placement of different tips having different configurations oforifices 50 to form different web configurations.

Vane 44 is thus adjustable in as least one of two modes. The vane can bepivoted so the tip can be moved closer to the exit of one die chamber orthe other causing a difference in die gap for the exits of each of thetwo matrix layers. This can result in a different matrix layer thicknessif each layer is made with matrix material having a similar meltviscosity. Alternatively, different exit gaps can result in a similarmatrix layer thickness if each layer is made with matrix material havinga different melt viscosity. The vane can also be adjusted by replacementof tip 53 with one having orifices of different shapes and spacing.

The interior construction of vane 44, and the position of vane 44 withindie 18, are more completely shown in FIGS. 3A and 3B, which arecross-sections of die 18. FIGS. 3A and 3B also show more clearly themanner in which the extrudable materials 15 and 17 are combined to makethe co-extruded polymeric web 12. Extrusion die 18 includes internalchambers 54A and 54B that are in part separated by vane 44. An internaldivider 57 is positioned and fastened within the die 18, and defines theextent of a portion of each of the chambers 54A and 54B. Chambers 54Aand 54B typically have a combined volume greater than vane 44, and thusupper gap 56 is formed above vane 44 and lower gap 58 is formed belowvane 44 Vane 44 is arranged such that it can move within chambers 54Aand 54B. In certain embodiments, vane 44 can be rotated about an axiscorresponding to the orifice 46 (shown in FIG. 2B).

Vane 44 contains a cavity 60 that is connected to the orifice 46. Cavity60 receives material 17, Which is subsequently forced under pressurethrough the plurality of exit orifices 50,(of which one is depicted incross section in FIG. 3A).

The sizes of the cross section of cavity 60 normal to the direction ofembedded phase material flowing into the cavity and the size and numberof exit orifices 50 are made to have sufficient pressure drop throughexit orifices 50 to yield the good width uniformity in the embeddedphases described above. These parameters are determined using the flowrate equation for a power-law fluid as described in Bird, R., et al.,Dynamics of Polymeric Liquids, Volume 1, Fluid Mechanics, 2d ed., JohnWiley & Sons, N.Y., 1987, p. 176$Q = {\frac{\pi \quad R^{3}}{( {l/n} ) + 3}( \frac{( {P_{o} - P_{L}} )R}{2\quad {mL}} )^{l/n}\quad \text{in which}}$

Q=volumetric flow rate, and is assumed equal for all exit orifices ofthe same size.

R=orifice radius

P_(o)=Pressure at beginning of tube or orifice

P_(L)=Pressure at end of tube or orifice

Po−P_(L)=ΔP

L=tube or orifice length

m and n are Power Law constants. For purposes of this description, n isnormally in the range of 0.2-0.8 and m is normally in the range of 3,000to 20,000. The calculation below uses m=11100 and n=0.28 which are goodapproximations for standard extrusion grade polypropylene.

Using this equation, the pressure drop of the flowing, embedded phasepolymer can be calculated${\Delta \quad P} = {( \frac{Q( {( {l/n} ) + 3} )}{\pi \quad R^{3}} )^{n}( \frac{2\quad {mL}}{R} )}$

For example, given: Q total polymer flow of 15 lb/hr, a polymer densityof 1 g./cm³, 95 exit orifices 50, R=1.9×10⁻⁴ m and L=5.13×10⁻³ m$Q_{T} = {{15\quad \frac{lb}{hr}} = {1.89 \times 10^{- 6}\quad \frac{m^{3}}{\sec}}}$$Q = {\frac{Q_{T}}{95} = {1.99 \times 10^{- 8}\quad \frac{m^{3}}{\sec}}}$${\Delta \quad P_{orifice}} = {{( \frac{( {1.99 \times 10^{- 8}\quad \frac{m^{3}}{\sec}} )( {\frac{1}{0.28} + 3} )}{{\pi ( {1.9 \times 10^{- 4}} )}^{3}} )^{0.28}( \frac{2( {11,100} ) \times 5.13 \times 10^{- 3}}{1.9 \times 10^{- 4}} )} = {6.87\quad {MPa}\quad \text{or 997 psi is the pressure drop through the exit orifices.}}}$

Using the same equation and solving for ΔP through a cavity of length0.4572 m (18 in.), inside radius of 0.0095 m:

ΔP_(cavity)=1.64 MPa or 238 psi

The ratio of pressure drop through the exit orifices to pressure dropthrough the cavity is about 4.

Using this type of calculation the ratio of ΔP_(orifice): ΔP_(cavity) ispreferably at least 1.5.

In addition, the exit orifices should be spaced apart from each otherenough so that the extruded embedded phases do not overlap or merge witheach other. Preferably the exit orifices,are spaced at least 4 mm fromeach other.

At the same time that material 17 is forced under pressure from vane 44,upper and lower gaps 56 and 58 provide a path for first material 15along the outside of vane 44. At point 55 in front of vane front portion53, the two materials 15 and 17 contact each other for the first time.Material 15 from top gap 56 within die 18 forms an upper layer 61 ofresulting web 12, and material 15 from bottom gap 58 of die 18 formslower layer 63 of resulting web 12 (as shown in FIG. 4). Between thesetwo layers 61 and 63 are discrete, discontinuous phases 59 of material17. The combined stream of first and second material 15 and 17 continuesto flow through die 18 until it leaves the die at exit port 30. Thedistance traveled by material 17 from leaving vane 44 until leaving die18 at exit port 30 can be either extremely short or quite long. In fact,in certain embodiments of the invention, front portion 53 of vane 44 ispositioned adjacent to exit port 30 of die 18. In other embodiments,front portion 53 of vane 44 is further removed from exit port 30,allowing a longer joint laminar flow of materials 15 and 17, as well aswidening (e.g., thinning) of the phases of material 17.

FIG. 3B shows die 18 having two orifices 26 and two orifices 28. Firstmaterial 15 enters die 18 at orifices 26 and then flows downstream untilit is joined by second material 17, which has flowed through vane 44after entering die 18 at orifices 28 which are connected to orifice 46.The two extrudable materials 15 and 17 flow together in substantiallylaminar flow through any remaining downstream portions of die 18, andsubsequently exit die 18 at exit port 30 to form co-extruded web 12. Web12 has a matrix of first material 15 formed by two layers and aplurality of discrete embedded phases 59 formed of second material 17.

The cross sections of discrete phases 59 typically do not have the exactsame shape as orifices 50 in tip 53 of vane 44. This is true in certainembodiments of the invention due to the widening of the flowing streamof material 17 after it has exited vane tip 53.

The present invention is advantageous in that materials 15, 17 areco-extruded in a controlled manner. The materials are brought togetherin the melt state, thereby allowing for improved adhesion to oneanother. In addition, even when the materials are not normallycompatible, they may still be co-extruded in order to produce a webretaining the properties of each of the materials. In the embodimentshown, the discrete embedded phases 59 have substantially uniform widthwhen the orifices in vane tip 53 are substantially uniform. Although thephases 59 are often uniformly spaced across the web 12, the width, andspacing of the phases can be altered by providing different tips 53 forvane 44. The large volume of cavity 60 where the second material firstenters vane 44 compared to the small volume of exit orifices 50 in thefront portion 53 of vane 44 is preferred in order to obtain a pressuredrop of the second material through the length of the cavitysubstantially less than its pressure drop through the exit orifices.

In addition, the configurations of the discrete phases may be varied byrepositioning vane 44 within die 18. In particular, vane 44 may berepositioned by slight rotation in order to alter gaps 56 and 58 nearvane 44 within chamber 60. In doing so, the thicknesses of the layers ofthe matrix in web 12 change. Gaps 56 and 58 can be changed in order toaccommodate extrudable materials having differing viscosities. Inembodiments where the matrix is formed of different materials to formthe two layers, a different material is fed into each of the twoopenings 26A and B and the gaps 56 and 58 can be adjusted in order tovary the thickness of each continuous matrix layer as desired. Gaps 56and 58 are adjusted by rotation of vane 44 such that one gap becomeslarger while the other gap becomes smaller.

Vane 44 is adjusted by rotation around an axis through opening 28 havinga pivotable fixture. If one matrix material is less viscous than theother, it is possible to narrow the gap through which the less viscousmatrix material flows in order to maintain uniformity of tile thicknessof each of the two matrix layers. The gaps can be altered duringprocessing in order to account for variations in processing conditions,such as changes in the temperature, pressure, flow rate, or viscosityover time. Thus, if die 18 has a warmer upper portion than lower portionresulting in lower viscosity of materials flowing through the upper gap,then the gaps can be adjusted to account for this change in viscosity.In addition, the gaps can be altered to achieve a different thickness ineach matrix layer. This is particularly useful when each matrix layer isof a different material, e.g., a thermoplastic elastomer and apressure-sensitive adhesive, where different properties are desired fromeach layer of the matrix.

In reference now to FIGS. 5A, 5B, 5C and 5D, various configurations ofvane tip 53 are shown that produce different coextruded webs. In FIGS.5A and 5B, the resultant web will have a multiplicity of discretepolymeric phases across its width. Each orifice of tip 53B is extendedas shown in FIG. 2C to minimize the contact time in the die between thediscontinuous phases and the layers of the continuous matrix. Tip 53Cshown in FIG. 5C will yield,.a plurality of discrete embedded phases oneach of the two edges of the extruded web, and tip 53D shown in FIG. 5Dwill yield one discrete embedded phase proximate each edge of the web. Aweb manufactured using tip 53D can be particularly suitable forcross-web stretching, since the thickened or reinforced portions on theedge of the web will provide a position onto which a stretchingapparatus (e.g., tenter clips) can grab when stretching the web in across-web direction.

The process of the invention is able to reproduce in the embedded phasesthe relative dimensions of the orifices in the tip to a degree that hasnot previously been known. In one aspect where the orifices havesubstantially the same dimensions, the width of the discontinuousembedded phases are remarkably uniform. As seen in the examples inTables 1 through 3 the coefficient of variation (COV) of the width ofany three consecutive discontinuous phases is less than 8, preferablyless than 5 and more preferably less than 3 percent when three or moresimilarly sized orifices are used. In Example 6 the same materials andprocess conditions were used as Example 1 and only the dimensions of theorifices in the vane tip were changed. Without any optimization ofprocess conditions, the resulting COV for the width of any threeconsecutive discontinuous phases was still under 8. This compares with aCOV of over 9 for the width of three consecutive phases formed withknown processes and materials such as shown in Comparative Example 1.Similar width reproduction is seen even when the orifices are unevenlysized or are less than three in number. When the uniformity becomes theconsistency of measurements of the same discontinuous region butrepeated over time at different down-web positions.

Another way of modifying the properties of the coextruded webs of theinvention is to use specific materials having desired properties for thelayers of the matrix and the embedded phases. Suitable polymericmaterials for forming the matrix layers and embedded phases of theinventive coextruded web are any that can be thermally processed andinclude pressure sensitive adhesives, thermoplastic materials,elastomeric materials, polymer foams, high viscosity liquids, etc.

“Pressure-sensitive adhesive” means an adhesive that displays permanentand aggressive tackiness to a wide variety of substrates after applyingonly light pressure. It has a four-fold balance of adhesion, cohesion,stretchiness, and elasticity, and is normally tacky at use temperatures,which is typically room temperature (i.e., about 20° C. to about 30°C.). A pressure-sensitive adhesive also typically has an open time tack(i.e., period of time during which the adhesive is tacky at roomtemperature) on the order of days and often months or years. An acceptedquantitative description of a pressure-sensitive adhesive is given bythe Dahlquist criterion line (as described in Handbook ofPressure-Sensitive Adhesive Technoloy, Second Edition, D. Satas, ed.,Van Nostrand Reinhold, New York, N.Y., 1989, pages 171-176), whichindicates that materials having a storage modulus (G′) of less thanabout 3×10⁵ Pascal (measured at 10 radians/second at a temperature ofabout 20° C. to about 22° C.) have pressure-sensitive adhesiveproperties while materials having a G′ in excess of this value do not.

“Nonpressure-sensitive adhesive” means nontacky polymeric materials,polymeric materials that are tacky when in the melt state but that donot display pressure sensitive properties, or other materials that haveadhesive properties at room temperature but do not meet the Dahlquistcriterion as described above. Such materials have a storage modulus (G′)of at least about 3×10⁵ Pascal (measured at 10 radians/second at a roomtemperature of about 20° C. to about 22° C.). These materials can benontacky thermoplastic materials, which can be elastomeric ornonelastoineric. Alternatively, they can be nontacky elastomers.

Suitable materials for use in preparing the webs of the presentinvention, whether they are pressure-sensitive adhesives ornonpressure-sensitive adhesives, are melt processable. That is, they arefluid or pumpable at the temperatures used to melt process the webs(e.g., about 50° C. to about 300° C.), and they are film formers.Furthermore, suitable materials do not significantly degrade or gel atthe temperatures employed during melt processing (e.g., extruding orcompounding). Preferably, such materials have a melt viscosity of about10 poise to about 1,000,000 poise, as measured by capillary meltrheometry at the processing temperatures and shear rates employed inextrusion. Typically, suitable materials possess a melt viscosity withinthis range at a temperature of about 175° C. and a shear rate of about100 seconds⁻¹.

Pressure-sensitive adhesives useful in webs of the present invention canbe any material that has pressure-sensitive adhesive properties asdescribed above at use temperatures, which are typically about roomtemperature (i.e., about 20° C. to about 30° C.). Generally, althoughnot necessarily, particularly useful pressure-sensitive adhesives areamorphous with a glass transition temperature (Tg) of less than about20° C.

The pressure-sensitive adhesive material can include a singlepressure-sensitive adhesive, a mixture (e.g., blend) of severalpressure-sensitive adhesives, or a mixture (e.g., blend) of apressure-sensitive adhesive and a material that is anonpressure-sensitive adhesive (e.g., a nontacky thermoplastic material,which may or may not be elastomeric), as long as the layer haspressure-sensitive adhesive properties. Examples of somepressure-sensitive adhesive blends are described in PCT Publication Nos.WO 97/23577, 97/23249, and 96/25469. Similarly, a suitablenonpressure-sensitive adhesive matrix layer can include a singlematerial that is a nonpressure-sensitive adhesive, a mixture of severalsuch materials, or a mixture of a material that is not apressure-sensitive adhesive with a pressure-sensitive adhesive, as longas the layer does not have pressure-sensitive adhesive properties.

Pressure-sensitive adhesives useful in the present invention can beself-tacky or require the addition of a tackifier. Such materialsinclude, but are not limited to, tackified natural rubbers, tackifiedsynthetic rubbers, tackified styrene block copolymers, self-tacky ortackified acrylate or methacrylate copolymers, self-tacky or tackifiedpoly-α-olefins, and self-tacky or tackified silicones. Examples ofsuitable pressure-sensitive adhesives are described in U.S. Pat. Nos. Re24,906 (Ulrich), U.S. Pat. No. 4,833,179 (Young et al.), U.S. Pat. No.5,209,971 (Babu et al.), U.S. Pat. No. 2,736,721 (Dexter), and U.S. Pat.No. 5,461,134 (Leir et al.), for example. Others are described in theEncyclopedia of Polymer Science and Engineering, vol. 13,Wiley-Interscience Publishers, New York, 1988, and the Encyclopedia ofPolymer Science and Technology, vol. 1, Interscience Publishers, NewYork, 1964.

Useful natural rubber pressure-sensitive adhesives generally containmasticated natural rubber, one or more tackifying resins, and one ormore antioxidants. Useful synthetic rubber adhesives are (Generallyrubbery elastomers, which are either inherently tacky or nontacky andrequire tackifiers. Inherently tacky (i.e., self-tacky) synthetic rubberpressure-sensitive adhesives include for example, butyl rubber, acopolymer of isobutylene with less than 3 percent isoprene,polyisobutylene, a homopolymer of isoprene, polybutadiene, orstyrene/butadiene rubber.

Styrene block copolymer pressure-sensitive adhesives generally compriseelastomers of the A-B or A-B-A type, wherein, in this context, Arepresents a thermoplastic polystyrene block and B represents a rubberyblock of polyisoprene, polybutadiene, or poly(ethylene/butylene), andtackifying resins. Examples of the various block copolymers useful inblock copolymer pressure-sensitive adhesives include linear, radial,star, and tapered block copolymers. Specific examples include copolymerssuch as those available under the trade designations Kraton from ShellChemical Co., Houston, Tex., and Europrene Sol from EniChem ElastomersAmericas, Inc., Houston, Tex. Examples of tackifying resins for use withsuch styrene block copolymers include aliphatic olefin-derived resins,rosin esters, hydrogenated hydrocarbons, polyterpenes, terpene phenolicresins derived from petroleum or terpentine sources, polyaromatics,coumarone-indene resins, and other resins derived from coal tar orpetroleum and having softening points above about 85° C.

(Meth)acrylate (i.e., acrylate and methacrylate or “acrylic”)pressure-sensitive adhesives generally have a glass transitiontemperature of about −20° C. or less and typically include an alkylester component such as, for example, isooctyl acrylate, 2-ethyl-hexylacrylate, and n-butyl acrylate, and a polar component such as, forexample, acrylic acid, methacrylice acid, ethylene vinyl acetate, andN-vinyl pyrrolidone. Preferably, acrylic pressure-sensitive adhesivescomprise about 80 wt-% to about 100 wt-% isooctyl acrylate and up toabout 20 wt-% acrylic acid. The acrylic pressure-sensitive adhesives maybe inherently tacky or tackified using a tackifier such as a rosinester, an aliphatic resin, or a terpene resin.

Poly-α-olefin pressure-sensitive adhesives, also called poly(1-alkene)pressure-sensitive adhesives, Generally comprise either a substantiallyuncrosslinked polymer or an uncrosslinked polymer that may haveradiation activatable functional groups grafted thereon as described inU.S. Pat. No. 5,209,971 (Babu et al.). Useful poly-α-olefin polymersinclude, for example, C₃-C₁₈ poly(1-alkene) polymers. The poly-α-olefinpolymer may be inherently tacky and/or include one or more tackifyingmaterials such as resins derived by polymerization of C₅-C₉ unsaturatedhydrocarbon monomers, polyterpenes, synthetic polyterpenes, and thelike.

Silicone pressure-sensitive adhesives comprise two major components, apolymer or gum and a tackifying resin. The polymer is typically a highmolecular weight polydimethylsiloxane or polydimethyldiphenylsiloxane,that contains residual silanol functionality (SiOH) on the ends of thepolymer chain, or a block copolymer comprising polydiorganosiloxane softsegments and urea terminated hard segments. The tackifying resin isgenerally a three-dimensional silicate structure that is endcapped withtrimethylsiloxy groups (OSiMe₃) and also contains some residual silanolfunctionality. Silicone pressure-sensitive adhesives are described inU.S. Pat. No. 2,736,721 (Dexter). Silicone urea block copolymerpressure-sensitive adhesive are described in U.S. Pat. No. 5,461,134(Leir et al.), PCT Publication Nos. WO 96/34028 and 96/35458.

Nonpressure-sensitive adhesive polymeric materials used in the webs ofthe present invention include one or more thermoplastic materials, whichmay or may not be elastomeric materials, and elastomers. These may beadhesive (i.e., tacky) when in the melt state or nonadhesive (i.e.,nontacky) materials, as long as the adhesive materials are not pressuresensitive, as defined above.

Thermoplastic materials are generally materials that flow when heatedsufficiently above their class transition temperature and become solidwhen cooled. They may be elastomeric nonelastomeric. Thermoplasticmaterials useful in the present invention that are generally considerednonelastoineric include, for example, polyolefins such as isotacticpolypropylene, low density polyethylene, linear low densitypolyethylene, very low density polyethylene, medium densitypolyethylene, high density polyethylene, polybutylene, nonelastomericpolyolefin copolymers or terpolymers such as ethylene/propylenecopolymer and blends thereof, ethylene-vinyl acetate copolymers such asthose available under the trade designation Elvax from E.I. DuPont deNemours, Inc., Wilmington, Del.; ethylene acrylic acid copolymers;ethylene methacrylic acid copolymers such as those available under thetrade designation Surlyn 1702 from E.I. DuPont de Nemours, Inc.;polymethylmethacrylate; polystyrene; ethylene vinyl alcohol polyestersincluding amorphous polyester; polyamides; fluorinated thermoplasticssuch as polyvinylidene fluoride and fluorinated ethylene/propylenecopolymers; halogenated thermoplastics such as chlorinated polyethylene;polyether-block-amides such as those available under the tradedesignation Pebax 5533 from Elf-Atochem North America, Inc.Philadelphia, Pa.

Thermoplastic materials that have elastomeric properties are typicallycalled thermoplastic elastomeric materials. Thermoplastic elastomericmaterials are generally defined as materials that exhibit highresilience and low creep as though they were covalently crosslinked atambient temperatures, yet process like thermoplastic nonelastomers andflow when heated above their softening, point. Thermoplastic elastomericmaterials useful in the multilayer webs of the present inventioninclude, for example, linear, radial, star, and tapered block copolymerssuch as those listed above with respect to pressure-sensitive adhesives(e.g., styrene-isoprene block copolymers, styrene-(ethylene-butylene)block copolymers, styrene-(ethylene-propylene) block copolymers, andstyrene-butadiene block copolymers); polyetheresters such as thatavailable under the trade designation Hytrel G3548 from E.I. DuPont deNemours, Inc., polyether block amides such as Pebax available fromAtochem, Philadelphia, Pa., ethylene copolymers such as ethylene vinylacetates, ethylene/propylene copolymer elastomers orethylene/propylene/diene terpolymer elastomers and metallocenepolyolefins such as polyethylene, poly (1-hexene), copolymers ofethylene and 1-hexene, and poly(1-octene); thermoplastic elastomericpolyurethanes such as that available under the trade designationMorthane PE44-203 polyurethane from Morton International, Inc., Chicago,Ill. and the trade designation Estane 58237 polyurethane from B. F.Goodrich Company, Cleveland, Ohio, polyvinylethers; poly-α-olefin-basedthermoplastic elastomeric materials such as those represented by theformula —(CH₂CHR)_(x) where R is an alkyl group containing 2 to 10carbon atoms, and poly-α-olefins based on metallocene catalysis such asEngage EG8200, ethylene/poly-α-olefin copolymer available from DowPlastics Co., Midland, Mich.

Elastomers, as used herein, are distinct from thermoplastic elastomericmaterials in that the elastomers require crosslinking via chemicalreaction or irradiation to provide a crosslinked network, which impartsmodulus, tensile strength, and elastic recovery. Elastomers useful inthe present invention include, for example, natural rubbers such asCV-60, a controlled viscosity grade of rubber, and SMR-5, a ribbedsmoked sheet rubber; butyl rubbers, such as Exxon Butyl 268 availablefrom Exxon Chemical Co., Houston, Tex.; synthetic polyisoprenes such asCariflex, available from Shell Oil Co., Houston, Tex., and Natsyn 2210,available from Goodyear Tire and Rubber Co., Akron, Ohio;ethylene-propylenes; polybutadienes; polybutylenes; polyisobutylenessuch as Vistanex MM L-80, available from Exxon Chemical Co.; andstyrene-butadiene random copolymer rubbers such as Ameripol Synpol1011A, available from American Synpol Co., Port Neches, Tex.

Forms are those materials made by combining the above polymericmaterials with blowing agents. The resulting mixtures are then subjectedto various changes known in the art to activate the blowing agent usedto form a multiplicity of cells within the polymer. Additionalcrosslinking may occur to cause resulting foams to be more stable. Aparticularly useful foam, when an elastic foam matrix is desired, isthat disclosed in Ser. No. 09/325,963, “Breathable Polymer Foams” filedJun. 4, 1999 and incorporated herein by reference.

High viscosity liquids are suitable as embedded phase materials. Theyare any liquids that do not diffuse through the matrix material andprematurely escape the article of the invention. These include, forexample, various silicone oils, mineral oils and specialty materialshaving a sharp melting temperatures around or below room temperature.

Viscosity reducing polymers and plasticizers can also be blended withthe elastomers. These viscosity reducing polymers include thermoplasticsynthetic resins such as polystyrene, low molecular weight polyethyleneand polypropylene polymers and copolymers or tackifying resins such asWingtack™ resin from Goodyear Tire & Rubber Company, Akron, Ohio.Examples of tackifiers include aliphatic or aromatic liquid tackifiers,aliphatic hydrocarbon resins, polyterpene resin tackifiers, andhydrogenated tackifying resins. Additives such as dyes, pigments,antioxidants, antistatic agents, bonding aids, antiblocking agents, slipagents, heat stabilizers, photostabilizers, foaming agents, glassbubbles, starch and metal salts for degradability or microfibers canalso be used in the elastomeric phase. Suitable antistatic aids includeethoxylated amines or quaternary amines such as those described, forexample, in U.S. Pat. No. 4,386,125 (Shiraki), which also describessuitable antiblocking agents, slip agents and lubricants. Softeningagents, tackifiers or lubricants are described, for example, in U.S.Pat. No. 4,813,947 (Korpman) and include coumarone-indene resins,terpene resins, hydrocarbon resins and the like. These agents can alsofunction as viscosity reducing aids. Conventional heat stabilizersinclude organic phosphates, trihydroxy butyrophenone or zinc salts ofalkyl dithiocarbonate.

Various additives may be incorporated into the phase(s) and/or thematrix to modify the properties of the finished web. For example,additives may be incorporated to improve the adhesion of thediscontinuous phases and the matrix to one another. The co-extruded webmay also be laminated to a fibrous web. Preferably, the fibrous web is anonwoven web such as a consolidated or bonded carded web, a meltblownweb, a spunbond web, or the like. The fibrous web alternatively isbonded or laminated to the coextruded web by adhesives, thermal bonding,extrusion, ultrasonic welding or the like. Preferably, the co-extrudedweb can be directly extruded onto one or more fibrous webs.

Short fibers or microfibers can be used to reinforce the embeddedphase(s) or matrix layers for certain applications. These fibers includepolymeric fibers, mineral wool, (glass fibers, carbon fibers, silicatefibers and the like. Further, certain particles can be used, including,carbon and pigments. Glass bubbles or foaming agents may be used tolower the density of the matrix layer or embedded phases and can be usedto reduce cost by decreasing the content of an expensive material or theoverall weight of a specific article. Suitable glass bubbles aredescribed in U.S. Pat. Nos. 4,767,726 and 3,365,315. Blowing agents usedto generate foams in melt processable materials are known in the art andinclude azodicarbonamides such as SAFOAM RIC-50 sodium bicarbonate-basedchemical blowing agent. Fillers can also be used to some extent toreduce costs. Fillers, which can also function as antiblocking agents,include titanium dioxide and calcium carbonate.

A number of additional steps can optionally be performed afterextrusion. For example, the web may be uniaxially or biaxially oriented,either sequentially or simultaneously, can be cured (such as throughheat, electromagnetic radiation, etc.), or can be dusted with varioustack-reducing agents.

The present invention is suitable for use in a number of applications.One application is an elasticized tab diaper fastener or closure. Tabdiaper closures are a portion of a disposable diaper that allows thefront and back of the diaper to be secured together when the diaper isplaced on a child. Tab diaper closures are typically permanently securedto one half of a diaper, and include an adhesive or mechanical fastenerthat permits fastening of the closure to the other half of the diaper asit is placed on a child. In order to keep the diaper snugly in place onthe child, it is preferable that the tab closure be elastic.

One or more discontinuous elastomeric phase(s) can be placed within anon-elastomeric matrix to form a web suitable for making an elasticdiaper closure tab. The elastomeric phase is preferably 10 mm to 50 mmwide for most conventional tape tab constructions. In one embodiment ofthe invention, a co-extrusion die of the invention is used to tore theelastic tab diaper closure. The embedded phase material is relativelyelastic, such as synthetic rubber. The matrix layer material isrelatively inelastic, such as polypropylene. These two materials areco-extruded using the apparatus and method of this invention such thatthe elastic material is substantially surrounded by the inelasticmaterial.

In FIG. 6A, an exemplary elastic diaper tab closure 70 is depicted. Tabclosure 70 has elastic phases 72 incorporated into an inelasticpolypropylene matrix 74. The elastic phases 72 are substantiallysurrounded by tile inelastic matrix material 74. In the embodimentshown, the inelastic matrix material above and below the elastic phasesis substantially thinner in the upper regions 76 and in the lowerregions 78 than the elastic phases 72 to permit easy stretching of thediaper tab in the regions where the elastic phases reside. Tile upperand lower regions 76 and 78 may each be between 1 and 2 percent of thethickness of the elastic phases 72 in certain embodiments, and may bebetween 0.5 and 10 percent of the thickness of the elastic phases 72 inother embodiments. In yet other embodiments, the upper and lower regions76 and 78 have substantially the same thickness as the elastic phase 72.

Referring to FIG. 6B, elastic diaper tab closures manufactured inaccordance with the invention may further include an additionalmaterial, such as non-woven substrate 80 formed on one or more sides ofthe elastic tab closure. Co-extruded materials 72 and 74 are extrudeddirectly onto non-woven substrates shown schematically as elongatablenon-woven substrates 80, thereby achieving an intimate bond to thematrix in the elastic section. Non-woven substrate 80 may be corrugatedprior to lamination to the matrix phase 76 in order to provide improvedelasticity of the tab closure 70, as shown in FIG. 6C. The non-wovensubstrate 80 allows for cloth-like softness and handling and allows webhandling in tie machine direction without substantial stretch.

The fibrous web in applications similar to that mentioned above can beelastic or inelastic and extensible. When the fibrous web is inelasticand extensible, the resulting composite laminate is generally inelasticwhen initially stretched in a cross web direction. However, a“preactivation” step can be provided to impart or increase theelasticity of the composite laminate. The preactivation step is broadlydefined as an operation performed on the fibrous web and or thecomposite laminate to generally weaken the strength of the fibrous weband/or inelasticly deform the fibrous web in the composite laminate inone or more directions. This allows the composite laminate to be moreeasily stretched while allowing reasonable recovery of the laminate toits original length when tension is removed. The prior art teachesseveral techniques wherein an inelastic fibrous web laminated to anelastic film is “activated”. U.S. Pat. No. 5,861,074, incorporatedherein by reference, discloses several ways to stretch a laminate inboth the machine and cross directions to impart or improve elasticity.U.S. Pat. No. 5,143,679, incorporated herein by reference, describes amethod and apparatus for incrementally stretching “zero strain” stretchlaminate webs to impart elasticity thereto in the direction of initialstretching. Alternatively, U.S. Pat. No. 5,804,021, incorporated hereinby reference, teaches that slits can be provided in the fibrous web toimprove elasticity in one or more directions of the composite laminateeliminating the need for “activation”.

In certain embodiments of the invention, the elastic tab closure isperforated in order to achieve breathability of the material. Theperforations are formed, for example, by use of means to form holesthrough the web such as sonic, hot needle, scoring, and pin rolls.

In yet another application of the invention, the method and apparatusare used to create a web having excellent tear resistance in the crossweb direction. As depicted in FIG. 7A, the web 82 has a plurality ofdiscrete embedded phases 84 spaced apart from each other in thecross-web direction. Discrete phases 84 are preferably resistant totearing (i.e., they reinforce the web). The discrete phases 84 aresurrounded by a continuous matrix 86. Discrete phases 84 are, forexample, ultra-low density polyethylene. Matrix 86 is, for example,polypropylene. The continuous nature of the matrix allows theincorporation of phases made of a material that has little affinity forthe matrix material. The phases are not able to delaminate from thematrix because they are encapsulated within the matrix. As such, theseencapsulated phases avoid problems associated with materials that areextruded onto or laminated to the matrix. For example, nylon phases maybe incorporated into a polypropylene matrix, even though nylon would notreadily be extruded onto or laminated to a polypropylene substratewithout delamination.

The web 82 is optionally stretched or oriented (in the machinedirection, transverse direction, or both) in order to improve itstensile strength. For example, the web 82 may be stretched in themachine direction from about 2 to over 8 times its original extrudedlength. The resulting web is suitable for use as a tear-resistant tapesuch as a strapping tape or a carry handle, or a tear-control tape toguide a tear along the surface of a pair of discontinuous phases.

Discrete phases 84 provide improved tear resistance. As a tearpropagates across the web in a cross web direction, the shear forces aredistributed across a larger area when the tear meets an interface formedby two materials poorly attached to each other. Web 82 is nearly flat,and therefore has properties suitable for subsequent application of arelease material and/or adhesives. In addition, web 82 can be relativelyeasily recycled, because in certain embodiments it is composed entirelyof polymeric materials. In contrast, certain prior art materials are notreadily recyclable because they contain incompatible materials, such asglass fibers, that provide the cross-web tear resistance.

Embodiments of the invention having this improved cross-web tearresistance are suitable for use as the closure for an easy-opening box.FIG. 7B shows a box 90 sealed with a web 92 (in the form of a tape)containing at least two embedded phases 94. The phases 94 a reformed bythe inventive process as substantially continuous discrete embeddedphases in a down-web direction within the web 92. The web 92 includes afinger lift that provides a tab 96 for lifting the end of the centerportion of web 92. As the tab 96 is lifted, because of the weakness ofthe bond between phases 94 and the matrix polymer, the web ruptures andthe tear can propagate along the embedded phases 94, thereby opening box90. The center of the web is lifted from the box 90, leaving behind thetwo edges of web 92. The remaining edges can possess a rough surfacethat allows the easy tearing of the remaining, tape in the cross-webdirection to facilitate opening of the box.

An alternative tape embodiment provides placing one or more embeddedphases near the surface of the web. In this embodiment, the web can beruptured by first pulling out an embedded phase, such as by grabbing aphase end and removing the phase from the tape web, leaving behind athin band of the web where the phase has been removed. This thin band issubsequently easily ruptured by, for example, snapping with a finger.This embodiment of the invention is suitable for use in securely sealingan envelope with an easy opening feature that also indicates tampering.Alternatively, one or more of the phases can be extruded from a polymercompound that includes a viscous liquid, such as silicone oil thatpreferably contains a pigment or dye. The phases are preferably sealedat various increments in the downweb direction, such as by heat sealingor crimping, thereby preventing accidental leakage of the liquid. Uponcutting or tearing of the web, the viscous liquid bleeds, or exudes fromthe ruptured phase and provides an indication of tampering.

Co-extruded webs formed using the apparatus and method of the inventionare also suitable for use in various medical articles, such as, wounddressings and tapes, surgical drapes, and wound closure systems. Incertain embodiments, phases are formed in the web matrix in order toprovide increased strength and improved handling without affecting theoverall conformability, transparency or breathability of the polymericmaterial. Preferred web matrix materials for use in constructing suchmedical articles include polyethylene, polypropylene, styrene blockcopolymers such as, for example, Kraton™ block copolymers polyester(e.g. made from Hytrel™ 4056 resin from Dupont, Wilmington, Del.),polyurethane, and combinations thereof Preferred embedded phasematerials for use in constructing such medical articles includepolyamide, polyethylene, polypropylene, polyester, and polystyrene. Inone preferred embodiment, non-breathable phases of polymeric material(e.g., Eastar™ 6763 polyester from Eastman Chemical Company, Kingsport,Tenn.) are formed in a breathable elastic web matrix (e.g., Estane™58237 polyurethane from B. F. Goodrich Company, Cleveland, Ohio) toincrease strength and aid in the ability to handle and position the webin final sheet or tape form. This represents a significant improvementover current webs formed of a breathable polyurethane that are difficultto handle because they are too flexible and thus do not easily maintaina shape. Surprisingly, the addition of non-breathable phases to thebreathable polyurethane web allows for retention of breathability (atleast 300 grams/square meter/24 hours, and preferably at least 1,500grams/square meter/24 hours by Moisture Vapor Transmission Rate—UprightMethod) while increasing cohesive strength and web handlingcharacteristics. In addition, the down-web tensile strength of theresulting webs typically is increased at least 500 percent overcomparable webs not having discontinuous phases and preferably isincreased at least 100 percent.

The precise extruders employed in the inventive process are not criticalas any device able to convey melt streams to a die of the invention issatisfactory. However, it is understood that the design of the extruderscrew will influence the capacity of the extruder to provide goodpolymer melt quality, temperature uniformity, and throughput. A numberof useful extruders are known and include single and twin screwextruders. These extruders are available from a variety of vendorsincluding Davis-Standard Extruders, Inc. (Pawcatuck, Conn.), BlackClawson Co. (Fulton, N.Y.), Berstorff Corp (N.C.), Farrel Corp.(Connecticut), and Mornyama Mfg. Works, Ltd. (Osaka, Japan). Otherapparatus capable of pumping organic melts may be employed instead ofextruders to deliver the molten streams to the forming die of theinvention. They include drum unloaders, bulk melters and gear pumps.These are available from a variety of vendors, including Giraco LTI(Monterey, Calif.), Nordson (Westlake, Calif.), Industrial MachineManufacturing (Richmond, Va.), Zenith Pumps Div., and Parker HannifinCorp., (North Carolina).

Once the molten streams have exited the pump, they are typicallytransported to the die through transfer tubing and/or hoses. It ispreferable to minimize the residence time in the tubing to avoidproblems of, for example, melt temperature variation. This can beaccomplished by a variety of techniques, including minimizing the lengthof the tubing. Alternatively, melt temperature variation in the tubingcan be minimized by providing appropriate temperature control of thetubing, or utilizing static mixers in the tubing. Patterned tools whichcontact the web can provide surface texture or structure to improve theability to tear the web in the cross web or transverse direction withoutaffecting the overall tensile strength or other physical properties ofthe product.

EXAMPLES

This invention is further illustrated by the following examples, whichare not intended to limit the scope of the invention. In the examples,all parts, ratios and percentages are by weight unless otherwiseindicated. The following test methods were used to characterize thearticles in the following examples:

Stress and Strain at Break

The web was conditioned for 24 hours at 23° C. (73° F.) and 50 percentrelative humidity (RH). Ten strips, each approximately 200 mm long and25.4 mm wide, were cut from the web in the machine direction using,razor blades. Each strip was placed in a dual speed tensile testingapparatus available from Instron Corporation, Canton, Mass. or MTSSystems Corporation, Sintech Division, Cary, N.C. With an initial jawgap of 100 mm, the cross heads separated at 50 mm/min for the first 5mm. The separation speed was then increased to 250 mm/min and maintainedat that speed until the strips broke. The tensile testing apparatus thencalculated the stress and the strain at break of the strip. Eachreported value is the average of measurements on ten strips.

Cross Tear Resistance

Strips of film were cut in the down-web direction to a length of about150 mm (6.0 in) and a width of 3.8 cm (1.5 in). A Plexiglas™ jig, cut inthe shape of a triangle, was used to mark two lines on a sample at 40degree angles from the down-web direction. The marks on the first sideof the sample were 5.1 cm (2.0 in) apart and on the second side were11.6 cm (4.56 in) apart. A nick was made with a razor blade on the firstside about 6.3 mm long and between the marks.

The sample was placed in the jaws of a tester, an Instron™ tensiletester available from Instron Company, set with a crosshead speed of 51cm/min (20 in/min), a jaw separation of 5.1 cm (2.0 in), chart speed of51 cm/min (20 in/min) and a load cell maximum of 90.7 kg (200 lbs). Thetwo reference lines aligned such that they were parallel to each jaw tocause the sample to be straight along the first side and form a naturalbend along the second side. The sample was forced to tear when initialstress was applied. The force was measured in lbs/in and converted intoNewtons/25 mm.

Tensile Strength and Elongation

Tensile strength and elongation in the down-web direction weredetermined in the following manner. A 10.2 cm long by 2.5 cm wide samplewas placed between the jaws of an Instron™ Tensile Tester to expose a5.1 cm gauge length. The crosshead and chart speeds were set at 25.4cm/min. The jaws were drawn apart at 25.4 cm/min until the machinedetected a break. Tensile strength, elongation, stress at break andstrain at break were calculated by the Instron™ software.

Moisture Vapor Transmission Rate (MVTR)

Moisture vapor transmission rates of the samples were tested usingeither the upright method (A) or inverted method (B) as described below.

A—Upright Method: Glass bottles were filled with approximately 50 mL ofwater. Three test samples and three control samples were cut into 3.8 cmdiameter samples using a round die cutter. The samples were placedbetween two foil rings which had holes cut in the centers. A rubbergasket was placed between the bottom of the foil and the glasscontainer. A screw cap with a 3.8 cm diameter hole was attached to theglass jar enclosing the foil-sample sandwich and gasket to the glass.The samples were conditioned for four hours at 40 degrees C at 20%humidity in a control chamber. The cap was then tightly secured to thejar and the jar was removed from the chamber and weighed on ananalytical balance to the nearest 0.01 gram. The jars were returned tothe chamber for at least 18 hrs. (at the conditions listed above). Thebottles were then removed and weighed immediately to the 0.01 g.Moisture vapor rates were calculated by the change in weight multipliedby the exposed area divided by the time they were exposed. Rates arereported in grams per square meter in 24 hours.

B—Inverted Method: The same procedure was followed as outlined above.However, after the samples were conditioned and weighed, they werereturned to the chamber and the bottles were inverted so that the watercontacted the test surface. The bottles were, left undisturbed for atleast 18 hrs. The bottles were then removed and weighed, and a moisturevapor transmission rate was calculated as above.

Peel Strength

Pressure-sensitive adhesive tape samples 1.25 cm wide and 15 cm longwere tested for 180° peel, adhesion to the surfaces of glass platesand/or smooth cast biaxially oriented polypropylene films. The sampleswere adhered to the test surfaces by rolling the tapes with a 2.1 Kg(4.5 lb.) roller using 4 passes. After aging at ambient temperatures(22° C.) for approximately 1 hour, the tapes were tested using a Model3M90 slip/peel tester, available from Imass, Inc., Accord, Mass., in180° geometry at 30.5 cm/min (12 in/min) peel rate, unless otherwisenoted.

Materials Used Material Description 7C50 Polypropylene/polyethyleneimpact co- polymer, Melt Flow Index (MFI) at 175° C. of 8, availablefrom Union Carbide Corporation, Danbury, Connecticut. Vector ™ 4211Styrene-isoprene-styrene block co-polymer, MFI at 200° C. of 13,available from Dexco Polymers, Houston, Texas. G-18 Polystyrene,viscosity of 780 Pascal seconds at 204° C. and shear rate of 100 1/sec,from Huntsman Chemical, Chesapeake, Virginia. 1015100SPolypropylene/titanium dioxide concentrate available from ClariantMasterbatches Division of Clariant Corporation, Holden, Massachusetts.Non-Woven A Carded, polypropylene Nonwoven, available from BBANonwovens, Simpsonville, South Carolina. Dypro ™ 3271 Polypropylene, MFIat 175° C. of 1.7, available from Fina Oil and Chemical Company, Dallas,Texas. Vector ™ 4111 Styrene-isoprene-styrene block co-polymer, MFI at200° C. of 11, available from Dexco Polymers, Houston, Texas. PS207Polystyrene, MFI at 175° C. of 15.5, from Huntsman Chemical, Chesapeake,Virginia. Engage ™ 8200 Ultra low-density polyethylene available fromDuPont Dow Elastomer, Wilmington, Delaware. Rilsan ™ BESNO P40 TL Nylon11 available from Elf Atochem North America, Philadelphia, Pennsylvania.Estane ™ 58237 Polyurethane available from B. F. Goodrich Company,Cleveland, Ohio. Eastar ™ 6763 PETG available from Eastman ChemicalCompany, Kingsport, Tennessee. Dowlex ™ 10462N High-density polyethyleneavailable from Dow Chemical Company, Midland, Michigan. Escorene ™ 3445Polypropylene, MFI at 175° C. of 35, available from Exxon ChemicalCompany, Polymers Group, Houston, Texas Tenite ™ 1550P Low-densitypolyethylene, Melt Index (MI) of 3.5, available from Eastman ChemicalCompany, Kingsport, Tennessee. PSA A An acrylic pressure-sensitiveadhesive (PSA) (95 weight percent isooctyl acrylate/5 weight percentacrylic acid, water emulsion polymerized, shear viscosity - 150 Pa-s),prepared according to U.S. Pat. No. RE 24,906, (Ulrich) and dried. PSA BAn acrylic PSA (96 weight percent isooctyl acrylate/4 weight percentmethacrylic acid, water suspension polymerized), prepared according toU.S. Pat. No. 4,833,179 (Young) which is dried to about 90 wt. percentand melt blended with Foral ™ 85 (a tackifying resin available fromHercules Inc., Wilmington, Delaware) in a wt. ratio of acrylate toForal ™ of 80:20. SAFOAM ™ Ric-50 A sodium bicarbonate-based chemical-blowing agent available from Reedy International Corp., Keyport, NewJersey.

Examples 1-2 and Comparative Example 1

Examples 1-2 demonstrate some effects of various process variables onconstructions having inelastic matrices and elastic embedded phases.

In Example 1, an extrusion was carried out using a 45 cm (18 in) wideCloeren™ two-layer multi-manifold die (available from Cloeren Co.,Orange, Tex.) that had been modified. The vane had been hollowed out asshown in FIGS. 3A and 3B, and the leading edge or tip had been cut offto make a vane manifold. A new vane tip containing five orifices wasfabricated and mounted to the vane manifold with a number of smallsocket head bolts. Preferably, these bolts were tightened with a torquewrench at a torque of about 11.3 Newton-meters (100 in. lb_(f)), inorder to prevent leakage. Five orifices were spaced across the vane tip,each having an oblong cross-sectional shape with a width of about 15 mm(0.600 inches), a height of about 0.38 mm (0.015 inches) and a spacingbetween orifices of about 76 mm (3.00 inches), respectively. The lengthof these orifices was about 6 mm.

An inelastic matrix material, 7C50 polypropylene/polyethylene (PP/PE),was fed with an extruder (64 mm (2.5-inch) Davis-Standard™ single screwextruder available from Davis-Standard Corp., Pawcatuck, Conn.) throughtwo inlet manifolds of the co-extrusion die. The matrix materialextruder was operated at 10 rpm with a head pressure of 9.0 MPa (1300psi) to feed matrix material at a rate of about 6.0 kg/hr (13.2 lbs/hr).An elastic phase material, a mixture of Vector™ 4211 SIS blockcopolymer, G-18 polystyrene and 1015100S white pigment concentrate in aweight ratio of 85:15:1 was fed with an extruder (38 mm (1.5-inch)Davis-Standard™ single screw extruder) through the modified vane in thedie. The embedded phase material extruder was operated at 40 rpm with ahead pressure of 3.2 MPa (470 psi) to feed elastic material at a rate ofabout 11.5 kg/hr (25.2 lbs/hr). Preferably, the extruder is operated tobring the flow rate of material through it gradually up to the desiredrate. Both extruders were operated using a temperature profile of zone1—163° C. (325° F.), zone 2—218° C. (425° F), zone 3—232° C. (450° F.)and zone 4—243° C. (470° F.). The die was operated at 243° C. (470° F.).The extrudate comprising a two-layer polymer matrix containing embeddedphases running down-web was extruded from the die into a nip formed by achrome casting wheel, at 7.2° C. (45° F.) and a silicone coated niproll, at 7.2° C. The web take-away or handling system operated at about16.8 m/min (55 fpm).

Example 2 was made as Example 1 except the continuous matrix materialextruder was run at 20 rpm with a head pressure of 12.4 MPa (1800 psi)to feed matrix material at a rate of about 11.8 kg/hr (26.0 lbs/hr).

Comparative Example 1 was made as Example 1 except a different die wasused and some conditions were changed. The extrusion was carried outusing a 45 cm wide Cloeren™ three-layer multi-manifold die that had beenmodified as described in U.S. Pat. No. 5,429,856 (Krueger), Example 1. A‘comb’ insert was bolted to the internal surface of one of the twounmodified vanes and snugly engaged with the second vane to allow thevanes to rotate in unison. The ‘comb’ insert had five orifices cut intothe metal which allowed material from the center manifold to flow intophases. The three center orifices had a width of 19 mm (0.750″ in) andthe two outside orifices of about 6.4 mm (0.250″ in). All the slots wereseparated by a space of 102 mm (4.00 in).

The matrix material was extruded through both of the outer manifolds andthe phase material was extruded into the middle manifold and through thecomb insert. The first outer layer was fed from a first extruder (38 mm(1.5-inch) Davis-Standard™ single screw extruder). The second outerlayer was fed from a second extruder (34 mm Leistritz™ fullyintermeshing, co-rotating twin screw extruder available from AmericanLeistritz Extruder Corp., Somerville, N.J.) fitted with a gear pump. Theembedded phase material was extruded with a 51 mm (2.0-inch) Berlyn™single screw extruder available from Berlyn Corp., Worchester, Mass.that was fitted with a gear pump to meter the material from theextruder. The first extruder was run at 15 rpm with a head pressure ofabout 9.7 MPa (1740 psi) to feed the first layer of matrix material at arate of about 3.2 kg/hr (7.0 lbs/hr). The second extruder had a screwspeed of 70 rpm, a gear pump speed of 7 rpm and a head pressure of 9.1MPa (1320 psi) to feed the second layer of matrix material at a rate ofabout 3.2 kg/hr (7.0 lbs/hr). The Berlyn extruder had a screw speed of19 rpm, a gear pump speed of 25 rpm and a head pressure of 9.5 MPa (1370psi) to feed the embedded phase material at a rate of about 11.4 kg/hr(25.0 lbs/hr). The web take-away system ran at a speed of about 9.1m/min (30 fpm).

The width in the cross-web direction for each example was measured foreach of the five embedded phases and an average, standard deviation andcoefficient of variation (COV) (standard deviation/average) in percentfor the three consecutive phases from similar sized orifices but havingthe greatest width variation were calculated for the width dimension.Results are reported in Table 1.

TABLE 1 Example 1 Comparative Ex. 1 Example 2 Width Width Width mm mm mmPhase 1 25.40 7.87 25.40 Phase 2 26.92 33.27 25.40 Phase 3 26.92 38.1025.40 Phase 4 28.45 31.75 25.40 Phase 5 26.92 7.87 23.81 Average 26.4134.37* 24.87 Std Dev 0.88 3.32* 0.92 COV (%) 3.32 9.65* 3.68 *Includesonly phases 2-4 because those phases were formed from orifices havingsimilar dimensions.

As seen in Table 1, the widths of the embedded phases in Examples 1 and2 were substantially uniform, indicating that the flow-rates to thosephases were substantially the same. In contrast, the widths ofComparative Example 1 varied substantially where the material came fromorifices having the same dimensions, as indicated in Table 1 by the COVvalues, indicating that the flow-rates to those regions hadsubstantially greater variation than Examples 1 and 2. White pigmentedembedded phase material had a definite boundary and did not extend intothe adjacent matrix material for Examples 1 and 2. For ComparativeExample 1, white pigmented phase material did extend into the matrixmaterial.

Examples 3-5

Examples 3-5 demonstrate changing melt viscosity of the embedded phasematerial on constructions having inelastic matrices and elastic embeddedphases.

Example 3 was made as in Example 1 except some process conditions werechanged. The matrix material extruder was run at 30 rpm with a headpressure of 15.2 MPa (2200 psi) to feed matrix material. The embeddedphase material extruder was run at 80 rpm with a head pressure of 13.8MPa (2000 psi) to feed embedded phase material. The web take-away systemran at a speed of about 16.8 m/min (40 fpm).

Examples 4 and 5 were made as in Example 3 except the material ratios ofthe embedded phase material were changed to alter melt viscosity. InExample 4 and 5 the weight ratios, of Vector™ 4211 SIS block copolymer(having a viscosity of 780 Pascal-seconds at a shear rate of 100 sec⁻¹at 204° C.), G-18 polystyrene (having a viscosity of 420 Pascal-secondsat a shear rate of 100 sec⁻¹ at 204° C.) and white pigment concentratewere in a weight ratio of 90:10:1 and 80:20:1, respectively.

The thickness and width in the cross-web direction for each example weremeasured for each of the five embedded phases and an average, standarddeviation and COV for the three consecutive phases having the greatestvariation were calculated for the width dimension. Results are reportedin Table 2.

TABLE 2 Thickness Width Example Avg in mm Avg in mm Std Dev in mm COV in% 3 0.19 34.40 0.92 2.66 4 0.18 38.63 0.92 2.37 5 0.20 34.40 0.92 2.66

As seen above, the phases became narrower as the viscosity of theelastomeric blend was reduced and wider as the viscosity was increased.

Examples 6-7

Examples 6-7 demonstrate the effect of vane tip design and selection ofextrudable materials on constructions having inelastic matrices andelastic embedded phases.

Example 6 was made as in Example 1 except the polystyrene was changed,the vane tip configuration was different and some process conditionswere changed. PS207 polystyrene was used in place of G-18 polystyrene.The exit orifices in the vane were 50% wider in cross-section (22.8 mm(0.900 in)) and four were used instead of five. The matrix materialextruder was run at 15 rpm with a head pressure of 10.4 MPa (1500 psi)to feed matrix material, and the embedded phase material extruder wasrun at 40 rpm with a head pressure of 3.2 MPa (470 psi) to feed embeddedphase material to the die. The web take-away system ran at a speed ofabout 15.2 m/min (50 fpm).

Example 7 was made as Example 6 except the materials were different andsome process conditions were changed. The matrix material was 7C50polypropylene/polyethylene copolymer and the embedded phase material wasVector™ 4111 SIS block copolymer, PS207 polystyrene (a pre-blendedmixture) and white pigment concentrate in a weight ratio of 85:15:1. Thematrix material extruder was run at 15 rpm with a head pressure of 10.4MPa (1500 psi) to feed matrix material, and the embedded phase materialextruder was run at 50 rpm with a head pressure of 3.7 MPa (540 psi) tofeed SIS/polystyrene/pigment blend. The web take-away system ran at aspeed of about 14.6 m/min (48 fpm).

The width in the cross-web direction for each example were measured foreach of the four phases and an average, standard deviation and COV forthe three consecutive phases having the greatest variation in percentwere calculated for the width dimension. Results are reported in Table3.

TABLE 3 Example 6 Example 7 Width Width mm mm Phase 1 33.34 57.15 Phase2 38.10 58.74 Phase 3 38.10 57.15 Phase 4 33.34 55.56 Average 36.5157.15 Std Dev 2.75 1.59 COV (%) 7.5 2.8

As seen, the width of the phases and the COV values were influenced byboth the materials and the vane tip configuration.

Example 8

Example 8 demonstrates that other webs can be laminated ontoconstructions of the invention. Example 8 was made as in Example 1except the matrix extruder speed was 15 rpm, the take-away speed was10.7 m/min (35 fpm) and two non-woven webs were laminated to the webconstruction. Two webs of Non-Woven A were fed into the nip to produce aconstruction having elastic phases uniformly spaced in an inelasticmatrix covered by non-woven material.

Examples 9-11

Examples 9-11 demonstrate some effects of having matrix materials andembedded phase materials that were different or similar where the matrixmaterials were inelastic and the phases were either elastic orinelastic.

Example 9 was made as in Example 1 except the vane tip configuration andmaterials were different, some process conditions were changed and somewere added. The vane tip had circular exit orifices each having adiameter of 508 microns (20 mils) and separated by a space of 4.1 mm(0.160 in) and extended from the vane tip 2.5 mm (0.100 in) into thematrix flow as shown in FIG. 2C. The length of these orifices was about5 mm. The matrix material was an inelastic thermoplastic, Dypro™ 3271polypropylene and the embedded phase material was Engage™ 8200polyethylene. The temperature profiles in both extruders were: zone1—191° C. (375° F.), zone 2—232° C. (450° F.), zone 3—271° C. (520° F.)and zone 4—271° C. (520° F.). The die was operated at 271° C. (520° F.).The matrix material extruder was run at 75 rpm with a head pressure of26.9 MPa (3900 psi) to feed matrix material. The embedded phase materialextruder was run at 41 rpm with a head pressure of 19.3 MPa (2800 psi)to feed embedded phase material. The web take-away system ran at a speedof about 3.7 m/min (12 fpm) resulting in a total web thickness of 533microns (21 mils). The resulting web was then stretched 6:1 in thedown-web direction. The orientation temperature was 115° C. (240° F.).

Example 10 was made in a manner similar to Example 9 except the embeddedphase material was different and some conditions were changed. Theembedded phase material was an inelastic thermoplastic, Rilsan™ BESNOP40 TL nylon. The stretch ratio was 5:1.

Example 11 was made in a manner similar to Example 9 except the embeddedphase material was the same as the matrix material, stretch ratio was7:1, and some equipment and conditions were changed. The matrix materialwas fed with an 88 mm (3.5-inch) Davis-Standard™ single screw extruderthat was operated with a temperature profile of zone 1—199° C. (390°F.), zone 2—216° C. (420° F.) and zones 3 to 6—238° C. (460° F.). The 88mm extruder was run at 16.2 rpm with a head pressure of 22.9 MPa (3320psi) to feed matrix material. The embedded phase material was fed with a51 mm (2.0-inch) Davis-Standard™ single screw extruder that was operatedwith a temperature profile of zone 1—182° C. (360° F.), zone 2—191° C.(375° F.) and zones 3 to 5—271° C. (460° F.) The 51 mm extruder was runat 17.4 rpm with a head pressure of 19.0 MPa (2750 psi) to feed embeddedphase material. The die was operated at 260° C. (500° F.). Theorientation temperature was 127° C. (260° F.).

Comparative Example 2 was tensilized polypropylene film (stretch ratioapproximately 7:1, thickness 84 microns) available as V/N 98105/06-1dfrom Nowofol, Siegsdorf, Germany.

Examples 9-11 and Comparative Example 2 were tested for Stress andStrain at Break and Cross Tear Resistance. Results are reported in Table4.

TABLE 4 Stress at Break Strain at Break Cross Tear Resistance ExampleMPa (kpsi) % N/25 mm (lb/in)  9 255 (37) 29 128 (28.75) 10 283 (41) 33237 (53.25) 11 414 (60) 34 5.5 (1.25) C-2 333 (48) 36 3.3 (0.75)

As seen in Table 4, the presence of the different inelasticthermoplastic embedded phases in Examples 9 and 10 reduced the stress atbreak of the web, but also significantly increased the cross tearresistance of the web. FIG. 8 shows a cross-section of Example 10. Theembedded phase material 102 is shown to have delaminated from the matrixmaterial by the space 104 between the embedded phase 102 and the matrix.A knit line between the two matrix material layers was still visibleeven though the layers were made of the same materials.

In addition, when the phases are of the same material as the matrix, thestress at break for tensilized web is significantly higher thantensilized web made without phases. The film of Example 11 was observedunder a microscope using cross-polarizing filters, and bands wereobserved in the film. When it was slit, strands of the embedded phasepolymer could be seen and separated from the film, indicating that,although the same polymer had been used for both phases, the matrixpolymer and the polymer leaving the vane did not if use together into asingle phase.

Examples 12-13 and Comparative Example 3

Examples 12-13 demonstrate characteristics of a web having elasticmatrices and inelastic phases.

Example 12 was made as Example 9 except the matrix material and embeddedphase material were different and some equipment and conditions werechanged. The matrix material was an elastic material, Estane™ 58237polyurethane. It was fed with a 51 mm (2.0 inch) Berlyn™ single screwextruder that was operated at a temperature profile of zone 1—149° C.(300° F.), zone 2—171° C. (340° F.) and zones 3 to 7—204° C. (400° F.)The 51 mm extruder was run at 25 rpm with a head pressure of 31.1 MPa(4500 psi) to feed matrix material. The embedded phase material was aninelastic thermoplastic polymer, Eastar™ 6763 glycol modified polyester.It was fed with an 32 mm (1.25-inch) Killion™ single screw extruder(available from Davis-Standard Killion Systems, Cedar Grove, N.J.) thatwas operated with a temperature profile of zone 1—188° C. (370° F.),zone 2—227° C. (440° F.) and zones 3 and 4—243° C. (470° F.). The 32 mmextruder was run at with a head pressure of 15.9 MPa (2300 psi) to feedphase material. The die was operated at 218° C. (425° F.). The webtake-away speed was 11.3 m/min (37 fpm) resulting in an overall matrixthickness of approximately 50 microns (2.0 mils). The cast web was notoriented.

Example 13 was made as Example 12 except the embedded phase material wasdifferent and some conditions were changed. The temperature profile forthe extruder that fed the matrix material was zone 1—149° C. (300° F.),zone 2—166° C. (330° F.) and zones 3 to 7—199° C. (390° F.). The 51 mmwas run at 10 rpm with a head pressure of 13.8 MPa (2000 psi) to feedmatrix material. The embedded phase material was an inelasticthermoplastic polymer, Dowlex™ 10462N polyethylene. The temperatureprofile of the 32 mm extruder that fed this material was zone 1—182° C.(360° F.), zone 2—241° C. (465° F.) and zones 3 and 4—249° C. (480° F.).The 32 mm extruder was operated at 12 rpm with a head pressure of 3.5MPa (500 psi) to feed phase material. The temperature of the nip rollswas approximately 16° C. (60° F.). The web take-away speed was 5.2 m/min(17 fpm) resulting in an overall matrix thickness of approximately 50microns (2.0 mils).

Comparative Example 3 was made by extruding the polyurethane matrixmaterial of Example 12 by conventional extrusion methods into a webhaving a thickness of approximately 25 microns (1.0 mils).

Examples 12-13 and Comparative Example 3 were tested for TensileStrength and Elongation and MVTR. Results are reported in Table 5.

TABLE 5 MVTR Tensile Strength Elongation g/m²/24 hrs ExampleMPa(lbs/in²) percent A B 12 38.6 (5600) 515 8900 NA 13 37.6 (5451) 498NA 1446 C-3 22.7 (3290) 545 7200 1800

As seen, the presence of embedded phases of inelastic thermoplasticmaterial significantly increased the tensile strength of the overallconstruction without reducing its moisture vapor transmission rate. FIG.9 shows knit lines from the web of Example 13. The embedded phasematerial 112 is embedded between the lower layer 114 and upper layer 116of matrix material. The two matrix layers 114 and 116 are joined suchthat a knit line between the two matrix layers was still visible eventhough the layers were made of the same materials.

Example 14

Example 14 demonstrates a construction in which the two layers of matrixmaterial are different.

Example 14 was made in a manner similar to Example 12 except the twolayers of matrix material were made of different materials and anadditional extruder (equipped with a gear pump to convey extrudate tothe die) was used. The first layer of matrix material was made of atacky elastomeric material, PSA B, and the second layer was made of theelastic thermoplastic polymer, Estane™ 58237 polyurethane. The firstmatrix material was fed with a first extruder, a 34 mm fullyintermeshing, co-rotating Leistritz™ twin screw extruder that used anincreasing temperature profile reaching a peak temperature of 193° C.(380° F.). The 34 mm extruder was run at 180 rpm with gear pump speed of4.7 rpm and a head pressure of 4.2 MPa (610 psi) to feed one matrixmaterial into the first matrix feed orifice 26A of the die. The secondmatrix material was fed with the 51 mm extruder into the second matrixfeed orifice 26B of the die

The resulting construction, which comprised a web having a PSA on oneside, a polyurethane on the opposite side, and polyester embeddedstrands, provides an example of a matrix composed of two differentmaterials.

Examples 1-16 and Comparative Example 4

Examples 15-16 demonstrate some effects of having tacky matrices andelastic phases.

Example 15 was made in a manner similar to Example 12 except the matrixand embedded phase materials were different and the process conditionswere changed. The matrix material was made of a tacky PSA A, and theembedded phase material was made of the thermoplastic polymer, Escorene™3445 polystyrene. The temperature profile for the extruder that fed thematrix material was zone 1—121° C. (250° F.), zone 2—149° C. (300° F.),zone 3—182° C. (360° F.), zone 4—204° C. (400° F.) and zones 5 to 7—210°C. (410° F.). The 51 mm matrix polymer extruder was run at 31 rpm, andit was equipped with a gear pump to convey extrudate to the die, saidpump running at a speed of 15 rpm and a head pressure of 10.4 MPa(1500psi) to feed matrix material. The temperature profile of the embeddedphase material extruder was zone 1—121° C. (250° F.), zone 2—193° C.(380° F.) and zones 3 and 4—210° C. (410° F.). The 32 mm embedded phaseextruder was run at 5 rpm with a head pressure of 3.4 MPa (490 psi) tofeed embedded phase material. The die temperature was 210° C. (410° F.)and the nip temperature was approximately 21° C. (70° F.).

Example 16 was made as in Example 15 except some process conditions werechanged. The 32 mm extruder was run at 10 rpm with a head pressure of4.5 MPa (650 psi) to feed embedded phase material.

Comparative Example 4 was made as in Example 15 except no embedded phasematerial was present and the 32 mm diameter extruder was not used.

Examples 15-16 and Comparative Example 4 were tested for Tensile Stressat Break and Strain at Break, using the Tensile Strength and Elongationtest, and Peel Adhesion to Glass. Results are reported in Table 6.

TABLE 6 Tensile Stress at Break Strain at Break Peel Adhesion ExampleMPa (psi) percent g/dL (oz/in) 15 4.5 (656) 858 25.2 (23) 16 6.2 (892)875 20.8 (19) C-4 0.5 (75)  743 26.3 (24)

As seen, the presence of the embedded inelastic phases resulted insubstantially increased tensile stress and strain at break without agreat deal of loss in peel adhesion to glass.

Example 17 and Comparative Example 5

Example 17 demonstrates the characteristics of a web having inelasticphases in foamed matrices.

Example 17 was made in a manner similar to Example 12 except the matrixand embedded phase materials were different and the process conditionswere changed. The matrix material was made of a pre-blended mixture ofinelastic thermoplastic polymer, Tenite™ 1550P polyethylene, andchemical blowing agent, SAFOAM™ Ric-50, in a weight ratio of 100:2 andthe embedded phase material was Teniter™ polyethylene alone. The 51 mmextruder was equipped with a gear pump to convey extrudate to the die.The temperature profile for the extruder that fed the matrix materialwas zone 1—121° C. (250° F.), zone 2—149° C. (300° F.), zone 3—182° C.(360° F.), zone 4—182° C. (360° F.), zone 5—221° C. (440° F.) and zones6 and 7—188° C. (370° F.). The 51 mm extruder was operated at 13 rpmwith a gear pump speed of 15 rpm and a head pressure of 10.4 MPa (1500psi) to feed matrix material. The temperature profile of the embeddedphase material extruder was zone 1—149° C. (300° F.), zone 2—204° C.(400° F.) and zones 3 and 4—216° C. (420° F.). The 32 mm extruder wasrun at 15 rpm with a head pressure of 13.8 MPa (2000 psi) to feedembedded phase material. The die temperature was 199° C. (390° F.) andthe nip temperature was approximately 21° C. (70° F.).

Comparative Example 5 represents a portion of Example 17 where therewere no phases embedded within the foamed matrix material.

Example 17 and Comparative Example 5 were tested for Stress and Strainat Break. Results are reported in Table 7.

TABLE 7 Stress At Break Strain at Break Example MPa (psi) percent 173.35 (485) 150 C-5 1.62 (235) 83

As seen, the presence of inelastic embedded phases within the foammatrix resulted in a tougher and more durable web construction.

We claim:
 1. A polymeric co-extruded web, the web comprising: aplurality of embedded phases, being separate from each other by beingdiscontinuous in the cross-web direction, the phases having a uniformwidth as shown by a coefficient of variation of less than 8 percent forthree consecutive phases; wherein the phases are substantiallycontinuous down-web and are surrounded by a matrix having at least twolayers.
 2. The polymeric co-extruded web according to claim 1, whereinthe coefficient of variance is less than 5 percent for any threeconsecutive embedded phases.
 3. The polymeric co-extruded web accordingto claim 1, wherein the embedded phases comprise an elastomeric materialand the matrix comprises a substantially non-elastomeric material. 4.The polymeric co-extruded web according to claim 1, wherein the embeddedphases comprise polyethylene, and the matrix comprises polypropylene. 5.The polymeric co-extruded web according to claim 1, wherein two layersof the matrix comprise different compositions.
 6. The polymericco-extruded web according to claim 1, wherein the embedded phasescomprise a substantially nonelastomeric material and the matrixcomprises an elastomeric material.
 7. The co-extruded web of claim 1having a pressure sensitive adhesive layer on one side of the web makingthe web useful as an adhesive article.
 8. The co-extruded web of claim 7wherein the adhesive article is suitable as a packaging tape, astrapping tape, a carry handle tape, a cross tear resistance tape, aneasy-opening tape or a tear indicator tape.
 9. The co-extruded web ofclaim 1, further comprising at least one fibrous web laminated to theco-extruded web.
 10. The co-extruded web of claim 1, wherein the matrixmaterial and the embedded phase material have the same chemicalcomposition, but can be distinguished as separate regions by observationunder a microscope using cross-polarizing filters.
 11. The co-extrudedweb of claim 1, wherein the web itself has been oriented by drawing theweb in at least one direction, down-web or cross-web.
 12. The web ofclaim 1, wherein the matrix is a breathable, elastic polyurethane, theembedded, discontinuous phases are thermoplastic, and the down-webtensile strength is at least 50 percent greater than a comparable webmade of the same breathable, elastic polyurethane but withoutdiscontinuous embedded phases.